1. Field of Invention
The field of the present invention relates in general to optical networks and more particularly to optical receivers.
2. Description of the Related Art
In communication systems light beams are increasingly used for transmitting information. The demand for communication bandwidth has resulted in a conversion of long and short haul communication trunk lines from copper to fiber optic (digital) communication. The wide spectral characteristics of fiber optics support broadband signals at very high data rates, gigabits per second.
Generally, an optical source, i.e. transmitter, converts an electrical signal, either digital or analog, to a modulated light beam which is then passed through an optical fiber to an optical detector, i.e. receiver, that extracts an electrical signal from the received light beam. A fiber may be shared with different communication channels using frequency, time or other forms of multiplexing. A typical optical link extends the range of a communication system with a transceiver unit that handles opto-electronic conversion between an optical fiber(s) and local area networks (LAN) on opposing ends of the fiber. Optical transceivers offer gigabit communication rates over long haul trans-oceanic cables or short range links in a metropolitan area.
Monitoring of optical transceivers is employed for diagnostic or preventive maintenance purposes. Monitored parameters include: laser bias current, transmit optical power, receive optical power, temperature, etc. A typical transmitter operates at a fixed power level. Since an optical link may range in distance from several meters to a hundred kilometers the optical receiver must function at a broad range of received signal strengths. Receiver monitoring is employed to assure the received signal is in appropriate range to ensure proper decoding of data at receiver.
What is needed are new means for monitoring optical receivers.